Conventional gun-type oil burners generally include an air tube having a fuel supply conduit extending axially within the tube. The fuel supply conduit is connected at one end to a fuel pump which supplies oil and terminates at its other end near the end of the air tube in a fuel dispensing nozzle which emits the oil under pressure. The oil is mixed with air which has been delivered by a centrifugal blower. The blower is driven by a motor which in some oil burner models also drives the fuel pump. An ignition transformer located on the oil burner is connected to an ignition apparatus which is located adjacent the fuel nozzle near the end of the air tube. This ignition apparatus ignites the oil-air mixture as it exits the air tube.
Previous oil burners have arranged the blower, motor, and fuel pump in various configurations. Some of the conventional oil burners have the inlet for the blower on the same side as the fuel pump. When bleeding air from the fuel pump, it is possible for air to be sucked into the blower thereby coating it with oil. This in turn causes severe problems with lint buildup.
A previous burner proposal has attempted to reduce the velocity of the flow of combustion air with the use of channels or baffles within the air tube just before the air reaches the location at which it is mixed with the oil and ignited. This may not produce a very substantial reduction in air velocity and can also result in stratification.
In order to adjust the amount of air which the burner takes in, previous proposals utilized a damper on the inlet side of the blower. When this damper is partially closed, thereby restricting the intake of air into the burner, the blower is not able to develop full capacity. This disrupts the flow of air through the burner by causing a small amount of air to flow too fast and without any chance to build up a good, full pressure head. It also contributes to velocity induced air stratification. In addition, such a damper location typically interferes with the connection of an outside air boot.
Moreover, with many prior burners, the location of the blower and fuel pump, as well as the damper, also interferes with the connection of a boot. Accordingly with prior burners, if there is a desire to connect an outside air boot to the burner, various parts of the damper and/or pump may need to be dismantled in order to achieve such a connection.
As with most mechanical apparatus, various rates of operation are desirable. Previous burner proposals have attempted to provide for adjustment of the burning rate by requiring dismantling of various parts and the use of awkward measuring tools. Many proposals require the burning rate to be adjusted at the rear of the burner which complicates measurement and verification of the burning rate at the actual combustion region.